It's much more reliable to use Rotom W to counter Talomflame than Rocks. A solid team will have a way to get rid of hazards, via Rapid Spin or Defog. Especially a team with Talonflame. And even with rocks up Talonflame can put in work. Getting rid of Rotom W would hurt OU more than it would help.
talonflame also happens to be squishy as hell, and relies on brave bird and flare blitz for damage; lots of things counter it. Rotom-W, on the other hand, is only countered by powerful Grass moves due to excellent coverage, and even then it can just volt switch out or trick a scarf onto them.
